Apparatus and method for the manufacture of nonwoven webs and laminate

ABSTRACT

Nonwoven laminates are made by a multi-station line comprising at least one spunbond die assembly and at least one meltblowing die assembly. Each station includes (a) a melt spinning die which can be selectively equipped with a spunbond die insert or a meltblowing die insert and (b) a moveable support structure for adjusting the proper die-to-collector distance, depending on the spunbond or meltblowing mode of operation. The multi-station line permits the selective manufacture of a variety of spunbond (S) and meltblown (M) laminates, including the S-M-S laminate.

BACKGROUND OF THE INVENTION

[0001] This invention relates generally to the manufacture of nonwovenwebs by meltblowing and/or or spunbond processes. In one aspect, itrelates to an apparatus with interchangeable meltblowing and spunbonddies. In another aspect, the invention relates to a novel filamentdrawing or stretching device. In still another aspect, the inventionrelates to the in-line manufacture of spunbond-meltblown laminates.

[0002] Nonwoven fabrics have received commercial application in avariety of industries ranging from medical, diapers, filtration,apparel, draperies, absorption, environmental, to name but a few of suchuses.

[0003] The term “nonwoven” refers to a sheet, web or batt ofdirectionally or randomly oriented fibers, made by bonding or entanglingthe fibers through mechanical, thermal, or chemical means. Nonwovenfabrics exclude paper and products which are woven, knitted, tufted, orfelted by wet milling. The fibers generally are man-made synthetics.

[0004] Although nonwovens may be made by a number of processes, the mostpopular processes currently in use are meltblowing and spunbondprocesses. Meltblowing is a process for the manufacture of a nonwovenfabric wherein a molten thermoplastic is extruded from a die tip to forma row of filaments (e.g. fibers). The fibers exiting from the die tipare contacted with converging sheets or jets of hot air to stretch ordraw the fibers down to microsize diameter. The fibers are thendeposited onto a collector in a random manner and form a nonwovenfabric.

[0005] The spunbond process involves the extrusion of continuousfilaments through a spinneret. The extruded filaments are maintainedapart and the desired orientation of the filaments are achieved byrotating the spinneret, by electrical charges, by controlled airstreams, or by the speed of the collector. The filaments are collectedon the collector and bonded by passing the layer of filaments throughcompacting roll and/or hot row calendering. Spunbonded webs generallyhave large average diameter (e.g. 12-100 microns, typically 15-50microns) which are heavier and stiffer then meltblown fibers (e.g.0.5-15 microns, typically 1-10 microns).

[0006] A paper presented at “Fiber Producer Conference 1983”, inGreenville, S.C., entitled “Nonwoven Fabrics: Spunbonded and MeltblownProcesses” describes the two processes in detail. The disclosures ofthis paper are incorporated herein by reference. It should be noted thatthe terms “fibers” and “filaments” when used in connection withnonwovens are interchangeable.

[0007] The meltblown fabrics are characterized as soft, porous with goodhand, but are deficient in strength properties such as tensile strengthand are not very wear resistant. On the other hand, the spunbond fabricspossess good strength properties and wear resistant but are not asflexible as meltblown fabrics.

[0008] It was discovered several years ago that the properties of themeltblown and spunbond fabrics could be combined by a laminateconsisting of at least one layer of the meltblown web and at least onelayer of the spunbond web. U.S. Pat. No. 4,041,203 discloses such alaminate. Over the years, improvements have been made in the laminate,the most popular being the so called S-M-S structure(spunbond-meltblown-spunbond) wherein a meltblown layer is flanked bytwo spunbond layers. The layers may be bonded together by compaction orby calendering, and exhibit outstanding strength properties, energyabsorption, tensile strength, and tear resistance, and yet possess asoft, flexible feel or hand.

[0009] The S-M-S structures can be made by laminating the preformed websor can be made by in-line operations wherein (a) spunbond filaments arelaid on a moveable collector forming a first layer, (b) meltblownfilaments are deposited on the first layer, and finally, (c) a secondlayer of spunbond filaments is deposited on top of the meltblown layer.The three layered structure then can be bonded together.

[0010] The in-line operation thus requires two spunbond apparatus andone meltblowing apparatus. The spunbond apparatus are large structuresbecause of the long distance of the collector from the spinneret and arenot readily adapted to other processes such as meltblowing. Themeltblowing apparatus, on the other hand, employs a relatively shortdistance from the die to the collector and is not readily adapted to thespunbond process. The in-line apparatus thus is restricted tomanufacturing only one type of laminate: the S-M-S laminate or portionsthereof.

SUMMARY OF THE INVENTION

[0011] It is an object of the present invention to provide an apparatuswhich features interchangeable dies. That is, a spunbond apparatus canbe readily converted to a meltblowing apparatus; or alternatively, ameltblowing apparatus can be readily converted to a spunbond apparatus.

[0012] It is further an object of the present invention to provide amulti-station, in-line spinning operation or method wherein each stationcan be selectively operated to produce a spunbond web, or a meltblownweb. The flexibility of each station permits the selective manufactureof a variety of laminates which include meltblown and/or spunbond layersin different combinations.

[0013] It is a further object of the present invention to provide ameltblowing die with a filament drawing device to increase the filamentdrawdown and produce finer filaments. The filament drawing device canalso be used with advantage on the spunbond apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]FIG. 1 is a side plan view of an in-line three station assemblyshowing the first and third stations in the spunbonding mode and themiddle station in a meltblowing mode.

[0015]FIG. 2 is a side plan view of the apparatus shown in FIG. 1showing the side view of the first station.

[0016]FIG. 3 is an enlarged front view of the melt spinning assemblyshown in each of the three stations.

[0017]FIG. 4 is an enlarged cross-sectional view of a portion (die body)of the melt spinning assembly shown in FIG. 3.

[0018]FIG. 5 is a cross-sectional view of the die body shown in FIGS. 3and 4 without a die-insert mounted therein.

[0019]FIG. 6 is a cross-sectional view of the die body shown in FIG. 5with the cutting plane taken along 6-6 thereof.

[0020]FIG. 7 is an enlarged view of a meltblowing die insert showndetached from the die body and shown in transverse cross-section.

[0021]FIG. 8 is an enlarged view of a spunbond die insert and shown intransverse cross-section.

[0022]FIG. 9 is a bottom plan view of the spinneret shown in FIG. 8.

[0023]FIG. 10 is an enlarged top plan view of the filament drawingdevice shown in FIGS. 1, 2 and 12.

[0024]FIG. 11 is a partial cross-sectional view of the filament drawingdevice shown in FIG. 10 with the cutting plane taken along lines 11-11thereof.

[0025]FIG. 12 is a side plane view illustrating a modified meltblowingdie assembly equipped with a filament drawing device shown in FIGS. 10and 11.

[0026]FIG. 13 is a fragmentary, enlarged view of a portion of thesupport structure illustrating a lifting jack for telescopically movingconcentric legs of the support structure.

[0027]FIG. 14 is a cross sectional view of a different meltblowing dieinsert.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] Because of the complexity of the structures embodied in thepresent invention, the invention will be described first, and withgeneral reference, to the three station in-line assembly (FIG. 1),followed by the description of the various components thereof, includingthe melt spinning assembly, the meltblowing die insert, the spunbond dieinsert, the filament drawing device, and an alternative design for themeltblowing assembly. Following the description of the variouscomponents, the operation of the assembly will be described illustratingthe flexibility of the multi-station line, particularly with respect tothe interchangeability of the dies at each station.

[0029] General Description of the Multi-Station Line (FIGS. 1 and 2)

[0030] The stations 10A, 10B and 10C of the multi-station line mayinclude many identical components. The same reference numerals willdesignate the corresponding component at each station. For example, theextruder at each station is designated by reference numeral 22.

[0031] Referring specifically to station 10A, this station comprises asupport structure which may be in the form of four vertical legs 11interconnected by cross beams 12. Each of the legs 11 are hollow and areconcentrically mounted over interior legs 13 which are anchored to thefloor. The legs 11 and 13 may be of any cross section but are preferablysquare and are sized to permit telescopic movement therebetween. Themeans for telescopically moving the outer legs 11 in relation to theinner legs 13 may take a variety of forms including hydraulic arms. Thepreferred means, however, is a conventional screw jack assembly 50located at the upper end of each leg 11 as illustrated in FIG. 13. Thejack assembly 50 comprises a gear box 55 driven by drive shaft 59 whichturns screw 60. Screw 60 is threaded to bushing 69 affixed to the upperend of leg 11. Turning the screw 60 in one direction raises the legs 11and support structure 15. Turning the screw 60 in the opposite directionlowers the legs 11 and support structure 15. The support structure 15and equipment mounted thereon is thus moveable vertically between anupper position (station 10A) and a lower position (station 10B).

[0032] A melt spinning assembly, shown generally as 16, is mounted onthe moveable support structure 15 by air pipes which include a pair ofvertical air pipes 18 (see FIG. 2) and a horizontal pipe section 19.There are two pairs of air pipes 18, one pair being mounted on each sideof the melt spinning assembly 16. One pair, shown in FIG. 2, isconnected to opposite ends of air box 20 of the melt spinning assembly16 as described in detail below. The horizontal pipe 19 of each pair ofpipes may be secured to cross beam 12. Thus the melt spinning assembly16 is suspended on the moveable support structure 15. (The term “meltspinning assembly” is used herein in the generic sense referring to bothmeltblowing and spunbond die assemblies.)

[0033] An extruder 22 is mounted on the moveable support structure 15 asillustrated in FIG. 2 and comprises hopper 23, barrel 24, and polymerfeed line 25. The polymer feed line 25 delivers polymer melt to the meltspinning assembly 16 as described in more detail below.

[0034] Positioned directly under the melt spinning assembly 16 and inalignment therewith are a pair of air quench ducts 26 and a filamentdrawing device 27. These two components, 26 and 27, are both supportedon a platform 28 in stacked relationship by brackets (see FIG. 2). Thepair of ducts 26 define a quench zone 49 therebetween. The drawingdevice 27 is also constructed as a pair of conduits defining a filamentdrawing or stretching zone 46 therebetween. The vertical space betweenthe quench ducts 26 and the drawing device 27 may include sheet metalhousing 47 and the vertical space between drawing device 26 and platform28 may include sheet metal housing 48. The platform 28 has an opening 32formed therein. The filaments 30 discharging from the melt spinningassembly the descend through the quench zone 45, housing 47, draw zone46, housing 48, opening 32 and are deposited on belt or conveyor 36. Thecomponents 26, 27, 47 and 48 are mounted on a wheeled carriage 33, asillustrated in FIG. 2, so that this assembly may be moved as a unit tothe operating position (FIG. 2) or moved at right angles to the conveyor36 to an inoperative position.

[0035] The conveyer 36 traverses all three stations as illustrated inFIG. 1 and is adapted to collect filaments from each station. Theconveyor 36 is perforated or a fine-mesh screen to permit the passage ofair therethrough. Vacuum means 25 positioned under conveyor 36 at eachstation may be used to withdraw the air and debris.

[0036] Air is delivered to the quenching ducts 26 as shown schematicallyat 34, and air is delivered to the filament drawing device 27 as shownat 35.

[0037] Station 10C is substantially identical to station 10A, both ofwhich depict the spunbond mode of the equipment mounted thereon. Themelt spinning assembly 16 at these stations are provided with spunbonddie inserts as described below.

[0038] Station 10B represents the meltblowing mode of the apparatus. Inthis mode, the carriage 33 and equipment mounted thereon is moved to theinoperative position and therefore does not appear in FIG. 1 for station10B. In this station, the moveable support structure 15 is moved to itslower position. The lower position of the moveable support structure 15is required because of the short distance between the meltblowing dieoutlet and the conveyor 36. The melt spinning assembly 16 of station 10Bis provided with a meltblowing die insert.

[0039] The operation of the three station line shown in FIG. 1 is asfollows: spunbond filaments 30 are deposited on the conveyor 36 forminga filament layer 42. Layer 42 is carried under the meltblowing die atstation 10B which deposits meltblown filaments thereon forming layer 43.These layers are carried under station 10C where another layer 44 ofspunbond filaments are laid thereon. As noted above, layers may befurther processed through calendering or compaction to bond themtogether.

[0040] Melt Spinning Assembly (FIG. 3)

[0041] The term “melt spinning” as used herein means the conversion of apolymer melt to filaments by extruding the melt through orifices. Thespinning assembly comprises a die assembly 51, positive displacementpump 52, motor 53, gear box 54, and shaft 56. The polymer feed line 25delivers polymer melt to the spinning assembly 16. Motor 53 drives thegear pump 52 which receives the polymer melt and delivers the same atmetered rates to the die assembly 51 which distributes and dischargesthe melt through orifices as filaments 30.

[0042] Air connectors 57 and 58 mounted on each side of the die assembly51 connect to the air lines 18 which delivers pressurized hot air to thedie assembly 51 in meltblowing mode.

[0043] The gear pump 52, motor 53, and gear box 54 may be similar tothat described in U.S. Pat. No. 5,236,641, the disclosure of which isincorporated herein by reference.

[0044] As best seen in FIG. 5, the die assembly 51 comprises a die body61 having a downwardly opening cavity 62 formed in its lower end. Diebody 61 may be constructed in halves as illustrated in FIG. 5, whereinone half has a polymer inlet passage 67 connected to line 25 for feedingthe polymer melt to the inlet of the gear pump 52.

[0045] The cavity 62 is defined by two elongate side walls 63 and topsurface 64. Elongate, v-shaped grooves 66 are formed on each side wall63.

[0046] The die body 61 has longitudinally spaced air passages 68 forinterconnecting air connectors 57 and 58 with opposite sides of thecavity 62.

[0047] As best seen in FIG. 6, the die body 61 has formed therein a“coathanger” distribution configuration comprising inlet 71, lateralchannels 72 and 73, the ends of which are interconnected with channel74. The area circumscribed by channel 72, 73 and 74 is specially shapedto affect a uniform distribution of the polymer entering inlet 71 tochannel 74, consistent with known coathanger type distribution systems.Holes 76 shown in FIG. 6 are adapted to receive bolts for bolting thetwo body halves 61 together. Electrical heaters may be mounted in thedie block 61 for maintaining the temperature of the die body at theoperating level.

[0048] Inlet passage 71 registers with the outlet of the gear pump 52 toreceive polymer melt therefrom and to distribute the same equally tochannel 74.

[0049] As mentioned previously, the air box 20 on each side of the diebody 61 is suspended between pipes 18. (See FIG. 2). As best seen inFIG. 4, each air box 20 defines an internal elongate square chamber 81which extends substantially the entire length of the die body 61 and isconnected to the air connector 57 through plate 82 as by weldedconnections.

[0050] Each connector 57 may be a welded assembly of plates 83, 84, 85and 86 which in combination define an internal air chamber 87 and isbolted to each side of body 61 by bolts 92. Plate 82 has a plurality ofair passage holes 88 distributed along the length thereof for feedingair from chamber 81 to chamber 87. Mounted within chamber 87 are baffles89 and 90 which define a tortuous flow path within chamber 87. Theoutlet for chamber 87 is provided by a plurality of air holes 91 whichregister with the plurality of air holes 68 formed in the die body 61.

[0051] The air passage 68 formed in each die half of body 61 extends tothe interior of the die body and forms a right angle discharge intocavity 62 as at 92. The right angle-turn in the flow passage 68 may besmoothed by the use of inserts 93 bolted to the die body as illustrated.

[0052] Air delivered to each connector 57 flows from the air chamber 81defined thereby inwardly to air passage 68 and enters the cavity at airpassages 92.

[0053] As indicated previously, the die assembly comprises die body 61and a die insert assembly 96 or 97 which fits into and is mounted withincavity 62. The insert assembly may be in the form of a meltblowing die(herein referred to as meltblowing die die insert 96) shown in FIGS. 4and 7 or may be in the form of a spunbond spinneret (herein referred toas spunbond insert 97) shown in FIGS. 8 and 9.

[0054] Meltblowing Die Insert (FIGS. 4 and 7)

[0055] Referring first to the embodiment using the meltblowing dieinsert 96, this assembly comprises a support member 98 (sometimesreferred to as a transfer plate) and a die tip 99 mounted thereon.Members 98 and 99 are joined by a series of bolts (one shown as 109).Member 98 has a top surface 101 which contacts surface 64 of cavity 62,and has side walls 102 which fit in close conformity with the side walls63 of cavity 62. Also formed in the support member 98 are a pair oflongitudinally extending V-shaped grooves 104. These grooves align withthe cavity grooves 66 with the insert 96 mounted in cavity 62. Aplurality of air holes 103 extend vertically through the support member98. The inlet of each air passage 103 is aligned with the outlet 92 ofeach air passage formed in the die body 61. Also formed in the supportmember 98 is an elongate channel 106 that extends through thelongitudinal axis thereof. The inlet of channel 106 registers withchannel 74 of the die body 61 with the meltblowing die insert 96 mountedin cavity 62 (see FIG. 4). An o-ring 107 surrounds the inlet 106.

[0056] The die tip assembly 99 comprises a die tip 107 and a pair of airplates 108. The die tip 99 has a downwardly projecting triangularnosepiece 111 defined by converging surfaces 112 and 113. Surfaces 112and 113 meet at apex 114, and a plurality of orifices 116 are spacedlongitudinally along the apex 114. A polymer flow channel 117 extendsthrough the die tip 99 and has an inlet which is aligned with polymerflow passage 106 of support member 98. The flow passage 117 pinches downto deliver polymer to the orifices 117. The nosepiece 111 may beintegrally formed in the die tip 99 as illustrated or may be a separatepiece bolted to the body of the die tip 99.

[0057] Also formed in the die tip 99 are air passages 118 which registerwith air passages 103 of support member 98. The air plates 108 aremounted on the die tip 99 by a plurality of bolts, one shown as 119. Theair plates 108 flank the nosepiece 111 and with surfaces 112 and 113define converging air gaps 121. Each air plate 108 defines with aconfronting surface of the die tip a tortuous air passage 124.

[0058] The meltblowing die tip insert 96 fits in close conformity incavity 62 of the die body 61. As described, the polymer flow passagesand air passages of the assemblies are respectively in fluidcommunication so that air flows through the assembly discharging fromair gaps 121 as converging air sheets at the apex 114 of the nosepieceas polymer flows from the gear pump 52 through the die body 61, themeltblowing die insert 96 discharging as filaments through orifices 116of the die tip.

[0059] The meltblowing assembly at Station 10B may include chilledquench air (secondary air) by separate air ducts (not shown) whichdischarge chilled air onto the filaments as they are extruded from theorifices 116.

[0060]FIG. 14 illustrates an alternative meltblowing die insert design.Corresponding parts illustrated in FIG. 7 are indicated by the samereference numerically in FIG. 14. The die insert is also described inmore detail in U.S. Pat. No. 5,145,689, the disclosure of which isincorporated herein by reference.

[0061] Spunbond Die Insert (FIGS. 8 and 9)

[0062] The spunbond die insert 97 comprises a support member 126 whichmay be substantially identical to support member 98 described previouslyexcept no air passages are formed therein. The support member 126,however, does have the top surface 127, side surfaces 128, and v-shapedgrooves 129 which may be identical surfaces 101, 102, and grooves 104,respectively of the meltblowing die insert 96.

[0063] Support 126 is provided with a polymer opening or channel 131which aligns with channel 74 of the die body 61 with the die insert 126mounted in cavity 62. Note that since there are no air passages insupport member 126, the air passages in the die body 61 are blocked offby surface 127.

[0064] The support member 126 is attached to spunbond spinneret 132which comprises a body member 133 and a spinneret plate 134 boltedtogether by a plurality of bolts 135. The body member 133 in combinationwith the plate 134 defines a feed chamber 136 having an inlet inregistry with passage 131 of the support member 128. The spinneret plate134 has a plurality of flow passages 137 formed therein which reducedown to orifices 138 at their outlets. As shown in FIG. 9, the orifices138 form a grid through which the filaments are extruded. The number andspacing of the orifices 138 may be in accordance with well knownspunbond practices. (See for example U.S. Pat. Nos. 4,340,563, 5,028,375and 5,545,371.)

[0065] Each of the die inserts 96 and 97 are selectively inserted intothe cavity 62 of the die body 61 and maintained there in place by a pairof square bars 141 which fit into square holes defined by v-grooves 66and 104 or 129 on each side wall of the cavity 62. With the selected dieinsert 96 or 97 in place and the bars 141 inserted, bolts 142 spacedtherealong, and threaded thereto on each side of die body 61 engage oneside of the bar 141 so that turning the bolts in one directionclampingly secures the insert sealingly onto cavity top surface 64.

[0066] The above description of the die body 61 and meltblowing andspunbond die inserts 96 and 97 makes it clear that the system can bereadily converted from one mode to the other by simply selecting theinsert die and inserting it into the cavity 62. This, of course,requires the adjustment of the moveable support structure 15 toaccommodate the operating mode. The means for inserting the die inserts96 or 97 into cavity 61 may be manual or automatic. Stations 10A and 10Cin FIG. 1 depicts the spunbond mode and station 10B depicts themeltblowing mode.

[0067] At station 10B, polymer melt is delivered from the extruder 22through the melt spinning assembly 16 provided with meltblowing dieinsert 96 and discharged as microsized filaments from the row oforifices 116. The filaments 116 are contacted on opposite sides byconverging hot air streams and carried to and deposited on the conveyor36. In the meltblowing mode, the moveable support structure ispositioned at its lower position.

[0068] For the spunbond mode of operation (stations 10A and 10B), thespunbond die insert 97 is inserted in the die body 61 and the moveablesubstructure 15 is moved to its upper position. The quench air assembly26 and filament drawing device 27 are positioned in place by moving thecarriage 33 to the position in FIG. 2. Air is delivered to the quenchducts 26 and to the drawing device 27 while filaments 30 extrudedthrough orifices 138 descend from the spinning assembly 16 through thequench zone 45 and drawing zone 46 and are finally deposited on theconveyor 36.

[0069] Filament Drawing Device (FIGS. 10 and 11)

[0070] The filament drawing device 27 serves to drawdown or stretch thefilaments of either the spunbond mode or meltblowing mode of operation.As illustrated in FIGS. 1 and 2, a pair of longitudinally extending airconduits 142 are disposed below the quench ducts 26. The air conduits142 are separated by space (the stretching zone 46), through which theextruded filaments pass. Each of the conduits 142 is connected to an airsupply 35 and, as shown in FIG. 11, comprises a rectangular chamber 144which receives air from two pipes 35 at opposite ends thereof. Eachconduit 142 is divided by a separation plate 147 into a second chamber146. Plate 147 has a plurality of holes 148 distributed longitudinallytherealong, providing fluid communication between chambers 144 and 146.Mounted in each chamber 146 are a pair of baffles 149 and 150 whichdefine a tortuous path for the air flowing through chamber 146. An endwall 151 defining chamber 146 is secured a pair of elongate members 152and 153 which in combination define a tortuous path for the air flowingtherethrough. A plurality of holes 154 formed in end wall 151 dischargeinto a plurality of air passages 156 which discharge into air passage159 defined by confronting surfaces of member 152 and 153. The outlet158 of the air passage 157 is directed downwardly with respect to thefilaments flowing through stretching zone 46. The angle of contact ofthe air discharging from the elongate passage 158 with respect to thefilaments passing therethrough should be between about 1 and 80 degrees(included angle β) preferably between 5 and 50 degrees, most preferably10 to 30 degrees.

[0071] As the filaments pass through zone 46, the converging air sheetsfrom passages 158 of each half of the drawing device 27 impart dragforces thereto and stretches or draws down the filaments to a smallerdiameter.

[0072] Meltblowing Die Assembly With Filament Drawing Device (FIG. 12)

[0073]FIG. 12 illustrates an alternative meltblowing mode of operation,wherein the melt spinning assembly 16 is provided with a meltblowing dieinsert 96 and is mounted above the drawing device 27. As illustrated,the device 27 may be mounted on the platform 28 which, as describedabove, is mounted on a carriage 33 for removing or inserting the device27 in the line. Sheet metal may be also used to define housings 38 and39 through which the meltblown fibers must pass. As the fibers passthrough housing 38, drawing zone 146 and housing 39, the downwardlyconverging sheets of air contact the meltblown filaments imparting dragforces to further drawdown the fibers. The additional drawdown by theuse of the filament drawing device produces microsized fibers in therange of 0.5 to 5 microns, preferably 1 to 2 microns.

[0074] Note that in this alternative mode of meltblowing operation, theDCD (die to collector distance) is much larger than the DCD forconventional meltblowing as is apparent by comparing station 10B withFIG. 12. With the drawing device 27, the DCD ranges from 3 to 8 feet,preferably from 3 to 7 feet, most preferably 4 to 6 feet.

[0075] Operation

[0076] Operating Parameters for the Spunbond Station(s)

[0077] The resin used in the spunbond die(s) can be any of thecommercially available spunbond grades, including a wide range ofthermoplastics such as polyolefis, polyamides, polyesters, PV A, PVC,polyvinyl alcohol, cellulose acetate and the like. Polypropylene,because of its availability, is the preferred thermoplastic. Theoperation parameters of the spunbond stations using polypropylene (MFR10 to 400) may be as follows: Broad Range Preferred Range Spinning Platelength (m) 0.5 to 6   0.5 to 4.5 width (in)  2 to 12 3 to 6 Orificesspacing (in)  0.05 to 0.250  0.1 to 0.125 diameter (in) 0.001 to 0.0400.016 to 0.020 Quench Ducts size height (m) 0.5 to 2   0.8 to 1.2 width(m) 0.5 to 6   0.5 to 4.5 Die to Collector (m) 0.1 to 5   0.1 to 2  Distance (DCD) Polymer Melt Temp. (° F.) 325 to 750 375 to 550 Rate(Gr./hole/min) 0.05 to 5   0.3 to 1.2 Quench Air Temp. (° C.)  2 to 20 5 to 15 Rate (SCFM/in)  1,000 to 20,000  5,000 to 15,000 Drawing DeviceTemp. Ambient Rate (SCFM/in)  1 to 100  5 to 20

[0078] The specification and operating parameters listed above are forpurposes of illustration. The spinning plate and chamber, as well as thequenching ducts may be conventional. Reference is made to U.S. Pat. Nos.3,692,618, 4.041,203 and 4,340,563, the disclosure of which areincorporated herein.

[0079] Operating Parameters for the Meltblowing Station

[0080] The meltblowing die (e.g. orifices, size and spacing) may beconstructed in accordance with a variety of designs including thosedisclosed in U.S. Pat. Nos. 3,972,759, 4,818,463, the disclosure ofwhich are incorporated herein by reference.

[0081] The specification and operating parameters listed above are forpurposes of illustration. The spinning plate and chamber, as well as thequenching ducts, may be conventional. Reference is made to U.S. Pat.Nos. 3,692,618, 4,041,203 and 4,340,563. the disclosure of which areincorporated herein.

[0082] Operating Parameters for the Meltblowing Station(s)

[0083] The meltblowing die (e.g. orifices size and spacing) may beconstructed in accordance with a variety of designs including thosedisclosed in U.S. Pat. Nos. 3,92,759 and 4,818,463, the disclosure ofwhich are incorporated herein by reference.

[0084] The meltblowing die may process any of the commercially availablemeltblowing grade thermoplastic resins. These include a wide range ofpolyolefins such as propylene and ethylene homopolymers and copolymers.Specific thermoplastics includes ethylene acrylic copolymers, nylon,polyamides, polyesters, polystyrene, poly(methyl meth-acrylate),polytrifluoro-chloroethylene, polyurethanes, polycarbonates, siliconesulfide, and poly(ethylene terephthalate), pitch, and blends of theabove. The preferred resin is polypropylene. The above list is notintended to be limiting, as new and improved meltblowing thermoplasticresins continue to be developed.

[0085] The preferred resin is a meltblowing grade of polypropylene. Thefollowing is an illustrative example of a meltblowing station: BroadRange Preferred Range Orifice Row (length) 0.5 to 6   0.5 to 4.6 metersmeters Orifice Diameter (inches) 0.010 to 0.050 0.01 to 0.2  (Typically0.015) Spacing (orifices/in) 10 to 40 20 to 35 Polymer Temp (° C.) 175to 300 200 to 270 Rate (Ger/hole/min) 2 to 5 0.3 to 1.2 Primary Air Temp(° C.) 175 to 300 200 to 275 Rate (SCFM/in)  2 to 100  5 to 30 QuenchAir (if used) Temp (° C.)  2 to 20  5 to 15 Rate (SCFM/in)  1,000 to20,000  5,000 to 15,000 Drawing Air Temp Ambient Rate (SCFM/in)  1 to100  5 to 20 DCD Distance to Collector  3 to 24  5 to 20 (inches) DCDDistance to Collector 2 to 6 3 to 5 (feet) (Intermediate setting)

[0086] Operating Procedure

[0087] The multi-station line shown in FIG. 1 illustrates the mode formanufacturing a spunbond-meltblown-spunbond (S-M-S) laminate. In station10A, the spinning assembly 16 is provided with a spunbond die insert 97and the moveable support structure 15 is adjusted to the upper positionto provide the desired DCD. The quench ducts 26 and filament stretchingdevice 27 are moved into place. In station 10B, the carriage 33 with theequipment mounted thereon has been removed and the melt spinningassembly 16 is provided with a meltblowing die insert 96. The moveablesupport structure 15 is positioned at its lower position placing thespinning assembly 16 at its proper meltblowing DCD. Station 10C isidentical to station 10A.

[0088] The operations are commenced by spinning continuous filamentsfrom the spunbond die 97 of station 10A. The filaments pass through thequenching zone 45 which not only cools the filaments but maintains themapart to prevent the filament from sticking together. The quenchedfilaments pass through the stretching zone 46 of device 27 where airdischarging therefrom further drawsdown and attenuates the filaments.The filaments are deposited on the conveyor 36 in a random fashion. Thespunbond filaments have an average diameter of 12 to 50 microns,preferably 15 to 40 microns. Air passes through the conveyor 36 and iswithdrawn by the vacuum system 25.

[0089] Layer 42 is conveyed under the spinning assembly of station 10Bwherein a microsized fibers having an average fiber diameter of 0.5 to15 microns, preferably 1 to 10 microns, most preferably 2 to 6 microns,is blown onto layer 42 forming meltblown layer 43 on spunbond layer 42.

[0090] The two layer laminate is then conveyed under Station 10C whereinanother layer 44 of spunbond filaments are deposited on top of themeltblown layer 43, completing the S-M-S structure. The three layerstructure may then be passed through a calendering or other device tobond the layers together in the conventional manner.

[0091] Based on the description contained herein, it will be readilyapparent to those skilled in the art that the apparatus of the presentinvention offers flexibility not attainable with prior art devices. Byselectively modifying the stations, the line can produce, in addition toS-M-S structure, the following laminates:

[0092] S-S, M-M, S-M, M-S using only two of the stations.

[0093] S-S-S, M-M-M wherein each layer may have different properties, oradditives, or colors.

[0094] S-S-M, M-S-M, M-M-S, S-M-M, M-S-S lamination using all threestations.

[0095] The following summarizes the more important features of thepresent invention:

[0096] (a) a moveable support structure for meltblowing or spunbond.

[0097] (b) a melt spinning assembly adapted to receive eithermeltblowing or spunbond die inserts.

[0098] (c) a meltblowing die having an auxiliary or supplementaryfilament stretching device. (d) a novel filament stretching device thatcan be used with spunbond or meltblowing dies.

1. Canceled.
 2. Canceled.
 3. Canceled.
 4. Canceled.
 5. Canceled. 6.Canceled.
 7. Canceled.
 8. Canceled.
 9. Canceled.
 10. Canceled. 11.Canceled.
 12. Canceled.
 13. Canceled.
 14. Canceled.
 15. Canceled. 16.Canceled.
 17. Canceled.
 18. Canceled.
 19. Canceled.
 20. Canceled.
 21. Amethod of manufacturing a thermoplastic nonwoven web using a meltspinning assembly adapted to interchangeably receive a meltblown dieinsert for meltblowing filaments onto a collector or a spunbond dieinsert for extruding filaments onto the collector, the methodcomprising: coupling the meltblown die insert to the melt spinningassembly; positioning the melt spinning assembly spaced relative to thecollector; adjusting the relative spacing between the melt spinningassembly and the collector to provide a first spacing between themeltblown die insert and the collector; meltblowing filaments from themeltblown die insert onto the collector; discontinuing the meltblowingof filaments from the meltblown die insert; replacing the meltblown dieinsert with the spunbond die insert; adjusting the relative spacingbetween the melt spinning assembly and the collector to provide asecond, larger spacing between the spunbond die insert and thecollector; mounting an air quench device and a filament drawing devicebetween the spunbond die insert and the collector; and extrudingfilaments from the spunbond die insert through the air quench device andthe filament drawing device onto the collector.
 22. A method ofmanufacturing a thermoplastic nonwoven web using a melt spinningassembly adapted to interchangeably receive a meltblown die insert formeltblowing filaments onto a collector or a spunbond die insert forextruding filaments onto the collector, the method comprising: couplingthe spunbond die insert to the melt spinning assembly; positioning themelt spinning assembly spaced relative to the collector; adjusting therelative spacing between the melt spinning assembly and the collector toprovide a first spacing between the spunbond die insert and thecollector; mounting an air quench device and a filament drawing devicebetween the spunbond die insert and the collector; extruding filamentsfrom the spunbond die insert through the air quench device and thefilament drawing device onto the collector; discontinuing the extrudingof filaments from the spunbond die insert; replacing the spunbond dieinsert with the meltblown die insert; removing the air quench device andthe filament drawing device; adjusting the relative spacing between themelt spinning assembly and the collector to provide a second, smallerspacing between the meltblown die insert and the collector; andmeltblowing filaments from the meltblown die insert onto the collector.